The statements made herein merely provide information related to the present disclosure and may not constitute prior art, and may describe some embodiments illustrating the invention.
It is known that in drilling some wells, sections of casing are run down a borehole, often with a float shoe at the lower end which is equipped with a double valve enabling the casing to fill with drilling mud both while the casing is moving down and also while it is stationary. Within the casing is a baffle collar which defines a socket for a latching dart carried by a plug. The plug and dart are driven down to the collar, when the pumping of cement into the casing has been completed, by a launching dart which also closes the passageway through the plug. U.S. Pat. No. 4,664,192.
Also known are well liner running shoes which include ports for discharging cement into the well annulus between the liner and the wellbore wall, a check valve to prevent reverse flow of fluid up through the interior of the liner and the workstring, receiver means for receiving a cement plug or “dart” and receiver means for receiving a running tool which may be disconnected from the shoe after the liner has been set in its predetermined position. U.S. Pat. No. 5,277,255.